Incandescent igniter



Fell. 18,1936.

R. REICHMANN INGANDESCENT IGNITER Filed Aug. 4, 1933 2 Sheets-Sheet =l Feb. 18, 1936. R.A REICHMANN INGANDESCENT IGNITER 2 Sheets-Sheet 2 Filed Aug. 4, 1935 yW..vM.V/////////////////w I W u A7///////%WM//// //////,7 \\\\\A\\ Patented seb. 1s, 193e mcANnEscEN'r IGNrrEa Reinhold Beichmann, Berlin, Germany, assignor to Siemens & Halske, Aktiengesellschaft, Siemensstadt, near Berlin, Germany, a corporation of Germany ApplicationAugust 4, 1933, Serial No. 683,608 In Germany January 5. 1933 19 claims.

lfor example, glow plugs such as areused for starting up and operating heavy oil engines and the like. Incandescent igniters of this kind are 5 often provided with a iilament of considerable thickness, which is arranged, for example, freely suspended in helical turns at the bottom end Vof the igniter. A chrome Vnickel alloy has proved to be the best material for the lament as it -is lo capable of withstanding comparatively high 'tem.

peratures without any special protection. The disadvantage oi chrome nickel and like laments, however, resides in their tendency to absorb carbon from the fuel or the lubricating oil, tending 15 to make the lament material brittle. Due to the percussions of the engine the lament is caused to vibrate and, having become brittle, tends to break. Moreover, the illament is subjected, in

rapid alternationatothe influence ofthe atomized m cool fuel and the hot combustion gases; it is unf able to withstand'the resultingextreme changes in temperature for any long period o1' time.

It has already been proposed to support the filament by disposing it on an insulator. lixperience has shown, however, thatjthe usual types of insulator bodies are unable to withstand the great strain resulting, particularly, from the abrupt and extreme changes in temperature "which occur during the operation of the engine.

a In addition, the chrome nickel wire or -iike material reacts under high temperatures towardthe silicated material of the carrier and is destroyed;

The present invention proposes an incandescent igniter wherein the lamen't is fired into a 85 ceramic body consistingof highly sintered metallic oxide or a mixture of several metal oxides.

Inthe accompanying drawings. Fig. 1 shows a longitudinal section' through an incandescent igniter; Fig. 2 illustrates a`modied form of the 40 incandescent body; Fig. 3 represents a longitudi'.

nal section of another form; Fig. 4 a longitudinal section oi anotherv embodiment of an incandescent igniter; and Fig. 5 illustrates a top view' ofA the corresponding incandescent body.

`45. In Fig. 1; numeral I denotes the casing of the igniter. 'Ihe incandescent body 2, which may be made of highly sintered alumina, together with lament 3, is arranged at the bottom end of the y. igniter and protrudes into the cylinderoi' the 60 engine. The ends or terminals of the" illament project slightly from the top of the ceramic body.V

, l (Cl. 123'145) My invention relates to incandescent igniters,

ably used in an embodiment wherein parts 5 and 'i consist of a comparatively .hard material, in which case the contact pieces are made-of relatively soft material, e. g., of copper or aluminum. Member 'in is pushed into the casing through a 5 screw joint .and presses both the incandescent -body 2 against packing 9, and the contact pieces `4 and 6 against the ends of the filament. The

metal member l is provided on its surface with an integral insulating layer lil, which serves the thev purpose of insulating the metal body from the centre pin and' from the igniter casing. In the case oi aluminum this can be an oxidized layer produced accordingto one -of the wellknown processes. The insulating materials gene erally used, such as mica; for. example, which are subject to changes under the iniiuence of heat, introduce difficulties in tightening the assembly 4 and also increase its cost, can thus be dispensed with. The centre pin 5 is connected to the cur- 20 rent supply at I3 and the metal body l at I i.

' In' Fig. 3v the incandescent body 2 is separately pressed against the packing 9 by means foi' a.

v member il; the current carrying'parts 5 and 'l Lare'likewise separately pressed against the ends 25 of the lament 3 by means of a cap nut i2. The

current conducting parts 5 and 'i are pressed into each other conically and are likewise provided with insulating surface layersformed homogeneously by the metal of which they are made. In the present case, vboth centre pin E and body I have this insulating layer on the outer surface. The' centre pin is driven into the outer body 'l and fits into the body 'i tight and in insulated relation thereto.

It is desirable to develop the heat as f ar as pos- "sible at the free end of the ceramic body and to to ensure a rapid heating oi the incandescent d0 igniter andl to avoid anv oxidation at the endsl of the lament projecting from the ceramic body as well as to attain a reliable contact at the ends of the lament.

To this end, the filament is so designed that Leasing i, and the incandescent body 2 with the illament 3. The ends II and I6 ofthe lament 50 are enlarged and taper to the operative heating cross-section 3. This iori'n of iilament may be obtained-by rolling or hammering the nlament body whichmaybe originally of auniformly -la'rge cross-section. Theenlargedends li and i6 55 are also embedded in the incandescent body with, the exception of the end portions of the filament which project from said body. The end l5 is in engagement with the central electrode 5. Since the ends i5 and I6 are spaced apart a distance less than the diameter oi. the central electrode t, the engagement of the enlarged end it with the outer supply member l is eected by securing a metallic plate il to the member 'l by means of a pin i8, and by causing the end it of the lilament to press against this metallic plate il. The Din i8 is insulated from the central electrode t by an intermediate layer i9. `The incandescent body 2 is held in msition by iianging inwardly the sleeve-like end of member l.

In this emboent the heat is substantially developed only in the thin cross-section of the filament and transferred along the shortest possible path to the incandescent body 2, whereas the enlarged ends i5 and it ruina cooler, and the portions of the ceramic body surrounding the ends become less heated.

The heating resistor with its enlarged ends consists of one piece; breakdowns are therefore avoided which may be caused in the case oi enlarged extensions, since such enlarged separately secured extensions due to the manner of attaching such to the filament by relatively unreliable methods,` e. g. by welding, soldering. clamping or the like. Contact resistance results also which may be considerable particularly upon applying small operating voltages.

Tungsten or molybdenum or alloys of these metals have been found to be suitable materials for the villament. Alumina, beryllia, magnesia and similar oxides or mixtures of several of these oxides may be used for the ceramic body. In' manufacturing the incandescent igniter, the lament may be wound in continuous turns of comparatively small diameter, as shown in Fig. 2, or in turns of a slightly larger diameter, with the other end passed back through the middle of the turns (Fig. 1). A bilar winding, as shown in Fig. 3, may also be used. The advantage of the latter is that the winding acts somewhat like' a. spring as soon as the ceramic body shrinks, the result being` that a straining of the lament is avoided. The lament body might, for instance, be disposed in the ceramic body by freely suspending it in a plaster mold and. lling the mold with a slip of the ceramic material, for instance,

alumina. The ceramic body on being dried and suiciently solidied, can be taken out of the moldtogether with the embedded heating resistance. The body may then be sintered at a temperature exceeding i600 degrees centigrade. e. g. at about i750". Sintering is preferably eiiected in a protective atmosphere in order to prevent the short ends of the heating resistance projecting from the ceramic body from being attacked. When ready, the body is :V r1 in the igniter casing, as shown in the dra.. The assembly is easily eiected.

Upon connecting the igniter to one olv the ordinary low tension current sources, the ent is heated; the heat thus created is rapidly transferred to the ceramic body surrounding the lament, and the ceramic body begins to glow after a. short time. Due to the good the conductivity of the highly sintered ceramic body it is only necessary to subject theiilament to a small excess temperature; the heating takes only a comparatively short time. With the engine in operation it is not the lament which acts directly as incandescent body, as in the case of access? former incandescent igniters, but vthe highly sintered ceramic body. The ceramic body can also be glazed. The incandescent body has a large and uniformly glowing surface. The body is neither affected by the high temperature prevailing within the engine, nor by the fuel or oil employed, nor by the combustion gases. Due to its high resistance against temperature changes it is insensitive to large temperature diierences between the hot combustion gases and the A atomized cool fuel. Since the highly sintered oxides, e. g. alumina, have a coeicient of expansion corresponding substantially to that of tungsten or molybdenum or alloys of these substances, there is no danger of the ceramic body' breaking in consequence of diierent expansion oi the lament. Owing to the fact that the lament is tightly embedded in the ceramic body, it is unaffected by the operating conditions occurring within the engine cylinders. In other words, they lament is embedded gas tight within the ceramic body and insulated thereby, and this condition will be true regardless of operating temperatures within the cylinder of an"'engme due to the aforementioned considerations. Breakage will therefore be prevented and continual performance mechanically and electrically will be maintained.

With incandescent igniters hitherto in use the glow temperature of the lament is relativelyl close to its melting point. In the incandescent igniter according to the present invention, the glow temperature is nowhere near the melting point of the filament or the sintering temperature of the ceramic body. An occasional higher load on the filament will, therefore, be of no detriment. With the incandescent igniters formerly in use anoverload frequently resulted in the destruction of the igniter device.

The new incandescent igniter improves the sensitive part and perfomance of heavy oil engines, and increases the reliabilityoi service.

l cl as my invention:

l. an igniter oi the class described comprising, a .teli-supporting ceramic body forming an incandescent member for direct operation within the cylinder of an internal combustion engine, and a illament disposed gas-tight within said body for incandescing said body.

2. An igniter of the class described comprising,

va self-supporting ceramic body consisting of highly sintered metallic oxide and forming a unitary incandescent member, and a lament consisting of a metal of the tungsten group disposed gastight within said body for incandescing said body.

3. An igniter of the class described comprising, a self-supporting insulating member consisting of highly sintered beryllium oxide and forming a unitary incandenscent body, and a illament consisting of a metal oi' the tungsten group disposed gas-tight within said body for incandescing n terminals.

6. An igniter of the class described comprising, a self-supporting insulating member formingan incandescent body for direct operation within the cylinder of an internal combustion engine la.-I ment means disposed gas-tight within said body for incandescing said body, the ends of said laf vment means projecting from said body and formfing terminals thereon, telescoping conductor means for supplying current to said terminals, a

v casing for holding said incandescent body and said conductor means, and means for effecting the engagement-of said conductor means withthe terminals oi' said incandescent body.

7. In an igniting device of the class described, an incandescent body, conductors for supplying current to said body, and insulating means between said conductors consisting of insulating layers formed homogeneously by the metal of said conductors.

8. In a glow plug of the class described,

incandescent body containing a lament and contacts therefor, members for supplying current to said contacts and said iilament', said mem bers being insulated from each other by means of an insulating layer on the surface of at least -one of said members and integral therewith.

, 9. In an igniter of the class described, a. seusupporting insulating member forming an' incandescent bodyI for direct operation within-the cylinder of an internal combustion engine, iilament means disposed gas-tight within said body for incandescing said body, the ends of said filament means projecting from said body and form.- ing terminals thereon, telescoping conductor means for supplying current to said terminals, means for insulating said conductors consisting of insulating layers formed homogeneously by the metal of said conductors, a casing for holding said incandescent body and said conductor means, and means for effecting the engagement of said conductor means with the. terminals-of said incandescent body.

10. An incandescent igniter comprising, an insulating member carrying a filament gas-tight embedded therein and forming an incandescent body therewith, terminals on said body associated with said filament, current conducting means for supplying current to saidterminals, Aa. casing for receiving said body and said current conducting means, means ilorl securing said body relative to said casing, and separate means :for effecting the engagement of said current conducting means with said terminals.

11. An igniter comprising, an insulating member containing'a lament embedded therein gastight and iormingtherewith an incandescent body arranged for direct operation within the cylinder ot an internal combustion engine, said iilament consisting of conductor means of predetermined cross section and having enlarged ends forming contacts on said body.

12. In an ligniter device of the class described, a unitary member forming an incandescent body for direct operation within the cylinder of an internal combustion engine and consisting of a rilament and an insulating body of metallic oxide arranged. to envelope the same gas-tight regardless of operating temperatures withinsaid engine, said lament being fixed within said body by sintering the same at a temperature above 1600 C. I

13. In a glow plug of the class described, a refractory incandescent body arranged to be disposed for operation directly within the cylinder ot an internal combustion engine, said body consisting ot highly sintered metallic oxide and a lament disposed within said body for incandescing said body to perform said operation within said cylinder, said body enveloping said iilament gas-tight regardless of operating temperatures of said body within said engine.

14. The process of making incandescent bodies of the class described, which consist in forming a resistor element, disposing said element freely within 'a mold, illling said mold with a plastic mixture consisting substantiallymf metallic oxide and embedding said element therein. drying the resulting body, and then sintering said body at a temperature above 1600 C.

15. A glow plug for internal combustion engines comprising, a lament, a carrier therefor, and a metallic housing for holding said carrier,

wherein said filament is Vgas tight encased in and protected by said carrier',l and electrically insulated irom said housing regardless of operating temperatures within saidy engine to which said carrier is subjected.

16. The structure dened in claim 15, wherein said carrier consists of highly sintered metallic oxide and forms a unitary body with the iilament encased thereby.

17. A device as deiined in claim 15, wherein said filament is coiled within said carrier.

18. A device as deilned in claim 15, wherein said iilament extends at one end of said carrier to the outside thereof and forms terminals thereon.

19. A devicevas dened in claim 15 wherein said lament extends at one end of said carrier to the outside thereof and forms terminals thereon, and 

